1. Field of the Invention
This invention relates to tin, lead, and tin-lead alloy electroplating baths using an alkane- or alkanolsulfonic acid as an acid component commonly capable of forming a soluble complex salt with divalent tin and lead.
2. Description of the Prior Art
In recent years tin and tin-lead alloy platings have found extensive use in producing coatings to improve solderability or forming etching resist films on electrical and electronic parts and the like.
For industrial production, borofluoride baths are widely employed to permit high-speed, uniform metal plating of tin, lead, or tin-lead alloy. However, the borofluoride baths are so corrosive and toxic that the equipment is costly and many difficulties are involved in the equipment and operation, including the disposal of wastewater. Although these problems are solved somehow or other using a highly advanced technique for treating the borofluoride, it would mean a heavy expense with much economic loss.